beginner MTB advice?

I bought a Redline D460 29er very recently and have tried hopping curbs and whatnot since I spend a lot of the time commuting in the city. That was fun, but I'm looking for more now! I've always ridden road bikes so mountain biking is very new and exciting.
I think I'll be doing cross country riding/or single track most of the time. Does anyone have some starter tips on what sort of techniques I should work on and how to work on them? Is it easy to bunny hop without being clipped in? etc etc THANKS!!